1. Technical Field
Various embodiments of the present invention relate to a nonvolatile memory apparatus and a method for controlling the same, and more particularly, to a nonvolatile memory apparatus for performing wear-leveling and a method for controlling the same.
2. Related Art
In general, a nonvolatile memory has been used as a storage memory of various portable information devices. Recently, a solid state drive (SSD) using a NAND flash memory in place of a hard disk drive (HDD) in a personal computer (PC) has been placed on the market, and is expected to rapidly make inroads into the HDD market.
Typically, when a semiconductor storage system, such as a SSD, controls a data file, actual data is written into, erased from, or updated in a page designated by a logical address that can identify the data file. More specifically, the logical address and a physical address of a data storage area are mapped through a flash translation layer (FTL). Then, when the logical address is referred to according to a command of a host, data may be written, erased, and read at a corresponding position designated by the physical address mapped with the logical address. The physical address, as used herein, may refer to positional information of a page or sub-block in a memory area.
In a case of NAND flash memory, wear-leveling is performed to uniformly maintain the lifetimes of cells.
In order to perform the wear-leveling, the erase count (EC) information of all blocks is stored in the NAND flash memory area, and loaded into a RAM buffer when the wear-leveling is required. Then, a replaceable block is searched for to change the physical position or physical address thereof.
With a recent trend toward a large capacity SSD, the number of blocks in the memory area has increased. Therefore, the memory of the RAM buffer into which the EC information of the entire blocks should be loaded is inevitably increased. Such an increase in memory of the RAM buffer, however, may be limited by the associated cost and available chip area, among other things.